In a regular pentagon ABCDE, Inscribed in a circle; find ratio between angle EDA and angle ADC.
Arc AE subtends ∠AOE at the centre and
∠ADE at the remaining part of the circle.
∴ ∠ADE =` 1/2 xx 72°`
= 36 [central angle is a regular pentagon at O]
∠ADC = ∠ADB + ∠BDC
= 36° + 36° + 72°
∴ ∠ADE : ∠ADC = 36° : 72° = 1: 2